1. Field of the Invention
The present invention relates generally to the field of cone crushers used for crushing rock, and other material. More specifically, the present invention discloses a hardfacing pattern for cone crusher surfaces in which a series of welded beads containing tungsten carbide particles are welded to the crusher surfaces with spacing between the beads.
2. Statement of the Problem
Cone crushers are typically used for crushing rock, ore, construction materials, and the like and have a cross-section similar to that shown in FIG. 1. The cone crusher 10 includes a mantle (or breaking cone) 30 mounted on a shaft 50, and a bowl liner 20 within which the mantle 30 is disposed. As shown in greater detail in FIG. 2, the mantle 30 has a generally convex annular or tapered conical shape that extends radially outward from an axis that is off-vertical. The upper surface of the mantle 30 functions as a crushing surface during operation of the cone crusher, as depicted in FIG. 1. The bowl liner 20 is normally mounted about a vertical axis and features a substantially concave annular crusher surface as shown in FIG. 3.
A motor drives the shaft 50 and mantle 30 to gyrate relative to the bowl liner 20. Rocks 40 or other material to be crushed are introduced into the hopper formed by the upper portion of the bowl liner 20. The rocks 40 fall into the space separating the mantle 30 from the bowl liner 20. The gyrating motion of the mantle 30 causes these rocks to be crushed between the mantle 30 and the bowl liner 20.
The crushing surfaces of both the mantle 30 and bowl liner 20 are made of a tough metallic material such as manganese steel. These crushing surfaces are frequently covered with a thin, continuous layer of a harder material (known as hardfacing) to enhance the wear characteristics of the assembly. For example, a continuous layer containing chromium carbide is sometimes applied to the crushing surfaces. The hardfacing can be applied by welding overlapping beads to form a substantially continuous layer over the manganese steel crushing surfaces.
A number of cone crushers have been invented in the past, including the following:
______________________________________ Inventor Pat. No. Issue Date ______________________________________ Axhelm 3,075,067 Jan. 22, 1963 Adam et al. 3,583,649 June 8, 1971 Werginz 4,168,036 Sep. 18, 1979 Arakawa 4,976,470 Dec. 11, 1990 Saari 5,115,991 May 26, 1992 Schwechten German OLS Nov. 19, 1992 4116374 ______________________________________
Axhelm discloses an automatic welding apparatus for making a continuous weld on the surface of a crusher roller. This results in a smooth hard surface on the worn roller (col. 1, lines 31-34).
Adam et al. disclose a wear part for use in a crusher. The crushing member is prestressed in compression sufficiently to overcome the tension stresses normally produced by the crushing operation. This prestressing may be accomplished by an annular band secured around the outer circumference of the crushing member.
Werginz discloses a cone crusher having an improved frame structure, an anti-spin mechanism, and an improved crusher setting indicator. FIG. 1 of the Werginz patent indicates that the crushing surfaces of the mantle 191 and the bowl liner 17 have a number of annular lips or edges.
Arakawa discloses a cone crusher having a gyrating mantle and a bowl liner above the mantle. The space between the mantle and bowl liner is automatically adjusted by hydraulic pressure that moves the bowl liner upward to accommodate load fluctuations and abnormal overloads.
Saari discloses another example of a gyratory cone crusher. The space separating the crushing surfaces can be adjusted by actuation of hydraulic cylinders pivotally connected to both the main frame and the bowl assembly.
Schwechten discloses a method for producing a wear-resistant surface by applying a coating of a hard material. Fields of hard material are obtained by filling the depressions formed by ridges of a buffer material connected with the base material of the machine part. The ridges of buffer material are formed by casting, machining, or welding. The hard material can be applied by casting or welding. The drawings suggest that the entire surface of the machine part is to be covered by the ridges and hard material. The invention is intended for use in roll mills, rock crushers, briquette and pellet presses, forging equipment, and other similar equipment.
Tungsten carbide has long been known to have a hardness close to that of diamond. Consequently, tungsten carbide has been used extensively for cutting or grinding in situations requiring extreme resistance to wear and abrasion. The following are a few examples:
______________________________________ Inventor Pat. No. Issue Date ______________________________________ Brady et al. 4,682,987 July 28, 1987 Hall 4,694,918 Sep. 22, 1987 Beakley 4,610,320 Sep. 9, 1986 Terrenzio 4,513,919 Apr. 30, 1985 ______________________________________
Brady et al. disclose a method and composition for producing hard surface carbide insert tools. A slurry coating containing hard nickel, metal alloy powder, and a fluxing agent is fused to bond an abrasive insert, such as tungsten carbide in a base metal matrix, to a cutting tool.
Hall discloses a percussion rock bit with a plurality of diamond tip inserts. The inserts have a cemented tungsten carbide body partially embedded in the steel bit and at least two layers at the protruding drilling portion of the insert. The outermost layer contains polycrystalline diamond. The remaining layers are transition layers containing a composite of diamond crystals and precemented tungsten carbide.
Beakley discloses a method for applying large tungsten carbide particles to the surface of stabilizer blades used in the drilling of oil, gas, geothermal and water wells. A soft, elastic metal powder is first applied to the substrate surface, as shown in FIG. 2 of the Beakley patent. Large tungsten carbide particles 20 that have also been coated with the soft powder are placed on top of the layer of soft powder, as shown in FIG. 3 of the patent. The tungsten carbide particles 20 are covered with additional soft powder, which is then fused to form a homogeneous mixture bonded to the substrate. A hard matrix 30 is applied and fused over the mixture 14 below, as shown in FIG. 5.
Terrenzio discloses a feed arrangement for a centrifugal rock crusher having a circular housing and an impeller that rotates concentrically. The impeller throws rock against an impact surface within the housing to crush the rock. Terrenzio further discusses that the wear life of the end surfaces 146 of the lip body 142 can be extended by imbedding an insert made of a hard material, such as tungsten carbide, within the end of the lip body 142 (column 9, lines 47-63).
3. Solution to the Problem. None of the prior art references uncovered in the search show a cone crusher having a metal hardfacing pattern made by welding staggered beads containing tungsten carbide particles to the crushing surfaces with spacing between adjacent beads to expose portions of the crushing surfaces. This is counter-intuitive in that incomplete covering of the crushing surfaces would generally be expected to reduce wear life. Instead, use of the invention in the field has consistently demonstrated that wear life is doubled or tripled over that of conventional cone crushers.
It is believed that the staggered beads in the present invention serve to reduce high stress patterns that otherwise occur within crushing surfaces having a continuous layer of hardfacing. These high stress levels can cause propagation of cracks that destroy the crushing surfaces. The welded beads in the present invention do not form a continuous layer, and therefore help to resist crack propagation through the crushing surfaces.
Another factor that may contribute to increased wear life in the present invention relates to the work hardening characteristics of the manganese steel commonly used to form the crushing surfaces. Manganese steel gradually hardens as it is subject to repeated deformation. However, in a conventional cone crusher, the manganese steel on the exposed top layer of the crushing surfaces may be worn away by the rock before significant work hardening can occur. Similarly, in a conventional cone crusher with a continuous layer of hardfacing above the manganese steel, the hardfacing is harder than manganese steel and tends to protect the underlying manganese steel from deformation and work hardening until the hardfacing has been worn away. In contrast, the spacing between adjacent welded beads in the present invention subjects the manganese steel substrate to significantly greater deformation during the crushing operation. This gives the manganese steel extensive time to work harden before the hardfacing pattern wears away. The welded beads in the present invention also serve to better grip the rock to produce a more uniform end product.